Pneumatically-controlled rheostat



Oct. 4 1,644,016

71927' l-l.` v. HAIGHT PNEUMATICALLY CONTROLLED RHEOSTAT Filed Aug.17. 1926. 2 Sheets-Sheet 1 oct. 4,1927. H V HMGHT 1,644,016

. PNEUMATICALLY CONTROLLED RHEOSTAT Filed Aue;.17, 1926 2 Sheets-Sheet 2 gg NQ resistance offthe invention willgbe in part obif'iousfand Hanny v. narcfnfr, or SHERBROOKE, eunnncwcanana Assrenon "11o aufwiesen? kanny 4contrameer JERSEY CITY, NEW Mineur, Aieonronarroniornnw JERSEY.

PNnUMnmIeALLYICONIBBQLLED `3HEusager.

Appliationfled lAugust 17, 1926. Serial No. 129,804.

This finvention 1relates to rheostats `and with respect to its more specifiofeatureysto pneumatically `operated apparatus 'for controlling 4said rheostats.

Anobjectof the invention isto enable a irheostat, more particularly .a liquid irheostat, o '.'fto be, operated pneuinatically and -to be 44controlled so @asto providelany desireddegree ofresistance. Another object ofthe inven-V ft-onlis zto enahletheoperator to adjust :the

rheostat to any prede tering'iied amount of Other objects and Jac lvantages .in part pointed out hereinafter.

In .the jdrawings forming a. part of `:the specification7 and in which similarreference characters referate` similar fparts.

Figure l isa side elevation partly in sec-` tionshowing la liqu1d'rheostat`and pneu- Tmaticallycontrolled apparatus thereior conrstructed in accordance with;the practice of the invention; Y

' Figure 12 `is a vertical sectionr lof .the

follow-up valve1t-aken alongthe line 2i-2 otFigure l lookingin the .directionof the 'Figure V5 .11s Iawhorizrontal Section .taken allongthe line 5-51of Figure lloolring 1n the (direction ofthe, arrows;

Figure 6 isalvertical section through -the switch control valves `taken along the lines AG--G of Figure flglooking inxthe'direction of the arrows and `Figure 7 is a vert-ical sectionthreuglnone ot fthe safety switch control .values `taken along` thelinesxT-T fof `lillgure 4l looling in i thedirection of the` arrows.`

.Referring to `the drawings, Athe .-rheostat comprises a tank Ausupported on Asuitable flcgs B. Vithin thetank Adis located a stationary electrode D which ,may be follned integral Vwith .the baseof .the tank, with which are adapted to cofoperateuaplurality fof movable electrodes r'lhe number of V the electrodes E depends upon the character iof the electric current. In this instance .there are three electrodes E. the .current being 'three-phase `and the leads K` `adapted cally within thetank A; The rods VF' are :provided with suitable bushings j J f of insulating .material .to prevent" shrt crcutng ofthe leadsK att-achedfto therods F. fPreferab ly the leaClSjCK are, flexible and clamped at the upper `end of the tube H by means of .fclai'npsL If desired, the leadsK .may pass vfrom tthe tank through the-*tube 'H -tof .the

theyare to convey current. t Theelectrodes may be of any suitable forni; in 'this instance they ,consist .of 'heavy Plates O l *formed integrally with a As]g ijde1` P attached to the lowerendsof therods F. A, split .cylindrical shelLQ- attached to theplat'es O and extending upwardlylherefromfprovides a ,large surface contact with a suitable .liuid `IR :providing the resistancepbetween the statipnaryelectrodes Dflndthe Inovable electrodes E. `The `fluid is prefera- Vbly .cooled .by Ya Yspirally: `disposed pipe S s ubrnenged'fin the fluid R 4and supplied with cooling water through a pipe connection T extendingg'througli the bottom ,pf'yth'e tank (The tube H lis bIiCed y' Etrein-.thel inside .ofthe tank by suitable f rods U extending .from the inside of the tank to the.tube I-I. Aconicalclover Vis provided t0 prevent foreign .inatter fromY entering the tank Al In order .to control ,the resistance yprovided by the rheostat, f leverW, pivoted preferably outside theftanlr isattached by `alpin X to thegspideri-G, iby .meanslof which the elec- ;trodesgE .are lifted or yloweredas desired.

A counter-balancing weight Y is provided Iatthe en clctlie ilever NV to facilitate the A raisingof the spider G and the parts ,at--

lcached thereto. Raisingand lowering ot lthe spider Gr iseii'ectedbya .pneumat'ically operated piston'Z'adapted tofreciprocate in c ylindervib suitably mounted :onV a base o attached to, one of .the legs B of the ytank A. The pistonfZ may be ofV any desired ,construction, :in this instanceQbeing provided with a cup; leather. al i held lin bplace byl a plate id .bQlQC-ltothelowerffacefof the piston. The

,upper end otthe piston ,Z is ,provided with a tube. f extending ffrom the .piston through the cylinderheacl g havinga glandli` and ill) suitable packing material y'. The piston rod 7c is attached at a ball and socket joint 0` to the piston Z and extends through the tube to connect with the longer arm' p of a bell crank attached` to a shaft g about which the bell crank turns. The shorter arm r of the bell crank is connected by a link s to the lever W.

The piston Z is double acting, and motive fluid for its actuation is admitted to the top of the cylinder b through a pipe t and at the lower end of the cylinder through a pipe u. rllhe motive fluid, preferably compressed air, for actuating the piston Z is controlled by an appara-tus comprising a hand-operated lever uY attached at one end to a link w connected toan operating arm mounted on a shaft y. The rotation of the shaft y and the and its exhaust therefrom.

gear .e rigidly mounted thereon causes rotation of a second shaft 2 by means of a pinion 3 keyed or otherwise suitably attached to the shaft 2. An arm 4 is attached to the shaft 2 and rotates therewith. An outwardly eX- ltending arm 5 on the shaft g provides a floating pivot-6 for a lever -7 adapted to bc raised and lowered by the arm 4 by means of a link 8. The position of the pivot 6 varies with the position of the lever 1V, and this variableleverage is utilized to control a follow-up valve hereinafter described.

The follow-up valve is shown in detail in Figure 2 and comprises a valve chest 9 having an inner chamber 10 connected by means of a pipe 11 to a port 12. A pair of'valves 13 and 14 controls the supply of motive fluid to the chamber 10 within the valve chest E) The valves 13 and 14 are provided with plungers 15 and 16, respectively, which are adapted to Contact with a cam 17 provided with a pivot 13 and actuated through an arm 19 formed inte-` grally with the cam connected by means of a link 20 to the floating lever 7. Motive fluid is supplied to the valve chest 9 through a pipe 21 connected at a chamber 22. TheV valve 13 controls communication between the chamber 22 and the chamber 10 leading to the pipe 11 and thence to the cylinder b;

Normall the valve 13 is held on its seat by means o a compression spring 23 within the valve chamber 10. The exhaust of motive fluid from the chamber 10 is controlled by the valve 14, which is adapted to vcontrol communication between the chamber 10 and a chamber 24 suitably connected to atmosphere. It will be seen that actuation of the plunger 15 by the cam 17 permits motive fluid to fiow from the supply pipe 21 into the chamber 10 and thence to the pipes t and u, supplying motive fluid to both Vends of the cylinder b andexposing the upper and lower faces of the differential piston Z to pressure.

lthe counterweight Y and lowering the spider rlfhe arm 4 is adapted to swing in either direction from its uppermost position to lower the lever 7. In Fig. 1 the arm 4 is shown swung in a clockwise direction. A similar movement in a counter-clockwise direction will also depress the lever 7 and produce a similar effect on the cam 17. The movement of the arm 4 is effected as has been above described by the longitudinal movement of the link fw. Itis intended that avertical position of the lever -o shall be the neutral position et which the electrodes Eare raised from the surface of the liquid R in the tank A. The apparatus is arranged to be associated with a double throw switch (not shown), as for instance a pneumatically operated switch of the character shown in copending application of Harry V. Haight, Serial No. 39,669, filed June 26, 1925.l

Means are provided by this invention to automatically throw the double throw removement of the lever o from its vertical or Vneutral position. To this end there isprovided apair of valves 3() and 31 (Figs. 6 and 3) controlling the supply of compressed air to a pair of supplyl pipes 32 and 33 respectively leading tothe reversing doublethrow switch. rllhe valves'30 and 31 are actuated by a cam 34 mounted on the shaft y and the dat face 35 of the cam 34 is adapted to lie horizontally, when the arm 4 stands vertically. Movement 'of the arm 4 in either direction from the vertically is accompanied by lan opposite movement of the cam 34 to open one of' the valves 30 and thereupon to admit motive fluid into one or the other of the pipes 32 and 33, resplectively, for actuating the reversing switc The valves 30 and 31 are mounted in a casing 36 supported by the main valve casing 9. The casing 36 is provided with a pair of chambers 37 and 38 connected with the pipes 32 and 33 respectively and controlled by the valves 30 and 31 respectively. A constant pressure chamber 39 into which both the valves 30 and 31 extend is supplied with motive fluid under pressure at all times, which is adapted to be admitted into the chamber 37 from the chamber 33 depending upon which of the valves 30 and 31 is lifted from its seat by the cam 34. Normally the valves 30 and 31 are held to their seat by means of springs 40 bearing against the heads of the valves and held in place by ca s 41 threaded into apertures leading to tlie chamber 39. The stems of the valves 30 and Y areipacked against leakage by suitable packing .42 compressedby means of glands 1 4a.

In lorder to assure that the reversing `switch will be thrown toits neutral position when `thefelectrode .E is in ,its uppermost l position, a `safety control device 44is .pro-

`vided in the `motive lluid supply pipes B2i ,-ancl. The safetyfcontrol device includes iapair of-valves 45.*(Figf7) which are adapted to exhaust the pipes 32 and 33 .ofvr any f fluid under pressure .which may have remained therein. The valves 45 areinclosed in a 4casing, 46 Yand .are ofthe poppet type 4eachfadapted toslide ,in .a cylindrical bore 47 Vof1 thecasingrt and seatas 'at 48-at the l mouth-.of achainber 49 into which the sup- AIC ,ply pipe y33 communicates. The pipe '33 leads l,out from the y chamber ,49, to the reversi ingswitch. ALikewise a corresponding pipe 2"leads to the reversing switch for eftt'ecting :its operation in the reverse direction.

1 -The^vali.ve,45 isnorm'ally held onto its seat :byfmeans ofa coil spring 50pressing against the head ofthevalve and removable "from the casing 46upon 'removal .of a Vplug 5l `threaded into ,an aperture 52 coaxial with the bore47. Ifthe valve is'lifted from its seat 48 any residual air under pressure in the pipes `33 and 335 `is adapted to flow into thelbore 47 around the reduced neck i :.5Qwof theya'lve and vthence Ito Iatmosphere throughsuitable portsfin the casing 46.

The :valves are adapted to 'be unseated' by 1 lmeans of a. nger 54 rigidlymounted on the shaft `g (Fig. 1)in such aposition thatthe finger 54 pressed againstthe valve 45 when y the `electrodesE Yare in their uppermost posir tion or when fthegpistonZ is in itslower- ,'most position'. Thus, if it is desired to break the "circuit by vraising the ,electrodes E out l of'the liquidR, the -reversingswitch vwill be ycaused `tofbreak the circuit'be'fore the. elecltrodes E .are again submerged inthe liquid .Means isprovided to prevent the revers-` ing switch from being operated 'by swinging i the lever o, from` one-extremeposition tothe other until the rheostathas caught up with the movement ofthe lever o. To this end there is provided a pair ofplungers v55 and 56.adapted-toproject into thejpath of a :plate 57 in the formof a sector of a circle (Fig. l).` Theplungersf55 Yand 56 are adapted to Vbe Iactuated by motive lluid supplied fromtli'e chambers '37 and '38 respectively Vin precisely 4the same -manneras the supp`y pipesflQ` and `33 respectively. Therba'se 58 supporting the vvalve casing 9 is ,provided witha pair o'fvtransverse bores 60in which the plungers 55 and 56 have a sliding lit.

The communicating passa-ges 61 connect the chambers L37 and 38 with: boresv 60 to supply ,fluid under pressure for depressing theiplungers. Normally the plungers are'lield'withvmeans of the valves 45.

drawn suitable coil springs f about ythe stems off-the plungers '55 and 56 to permitthe arm 4 to move in either direction as shown-in `Fig.l 8. Having moved the arm `4 Jin unedirection, however, Y as for vinstance shown in LFig. l, the 4plufng'ger 56 will be depressed by Vmotive fluid supplied from the 'chamber' 38 past the valve ltocause the stem of fthe plunger 56 toprojectintothe pathof-the plate57. Consequently, the arm 4-cannotf be pressingthe lever 7 by means ofthe link 8.

This causes the link 2O to rotate fthe cam 17 .to unseat the valve 14 permitting-motive fluid to flow from'f'the chamber 10 inthe valve casing 9 (Fig. 2) into-the piped-leading to the' ower part yof the cylinder The piston Z is thereupon raised lifting :the bell crank p `and i' mounted onthe shaft g and .raising thepivot 6 onthevend ofthe arm 5. This raises the free end oftlie floating "lever 7 and likewise "pulls `the link 20 4upwardly causing-the cam fto resume aneutralpositionand permitting the valve 14 to close, shutting off the supply of motive Huid to the cylinderli. The swinging ofthe f'bell crank p and i" raises tlie lever l/Vto' depress theelectrodese "into the liquid. The Cepth .of yimmersion of the electrodes e will depend V'upon the extent to which the'control lever 'u is moved.

Simultaneously. the cam 84 is -iievolved depressing the plunger ofthe valve V3l and permittingmotivefluid to l`flow into the pipe lto operateithe ireversing switch Vwhich closes ltliemain circuit-of which therheostat herein ldescribed providesresistance. The lever o may be moved instantly to any position to t-he left of the lvertical biitris `stopped A'from being moved beyond that position which would operate' the valve 30 by the cam 34, by means of the stop Vplunger 56 .which is depressed by motive lfluid entering the passage 6l into'the'bore'6U-and pressing l the plunger 56 outwardly. Movement of the lever if tothe `right of the center is only possiblea'f'ter the electrodes E have been raised out of the fluid "R to break thel electrical circuit. -In thisfposition the-linger 54 depresses both of'thevalves 45-jviermittingany residual Vmotive ffluid to `escape from the Avpipes 33-and fromthebore'iGO;V The fplungers 55 and 56 are thereupon released and movement of the lever v to the right is permitted. Y

On approaching the central neutral position of the lever' o from any position, the arm 4 raises the link 2O which causes the cam 16 to depress the upper valve 13. The return of the cam 17 to its normal position is effected by the admission of motive fluid from the chamber 10 past the valve 13 into A the pipe 21 communicating with the pipe z5 to admit motive fluid above' the piston Z pulling downwardly on the connecting rod lc to raise the electrodes E.

v The advantages of the apparatus will be apparent. lt is impossible to reverse ihe reversing switch until the circuit is brolien at the rheostat. Furthermore any desired gradation of resistance by simple noveme'iit of the control lever remote from the rheostat itself may be made.

I claim:

1. A pneumatically controlled rheostat comprising a tank containing liquid and electrodes adapted to be immersed. in said liquid, a hand operated lever having positions corresponding to definite depths ot immersion of said electrodes inv said liquid, a cylinder and fluid actuated piston adapted to raise and lower said electrodes iu said liquid, and valves adapted to be'actuated by saidhand operated lever and restored to inoperative position by said piston, to con# trol the raising and lowering ot said piston in said cylinder `for setting said electrodes at the position corresponding to the position of said hand operated lever.

2. A pneumatically controlled rheostat comprising a tank, containing liquid and electrodes adapted to be immersed in said liquid, a cylinder and fluid actuated piston adapted to raise and lower said electrodes in said liquid, a'liand operated lever having positions corresponding to delinite depths of immersion of said electrodes, valves for controlling the flow of motive fluid to said cylinder, and a cam for actuating said valves,

operable by said hand operated lever and restored by the motion of said piston.

3. A pneumatically controlled rlieostat comprising a tank containing liquid, electrodes adapted to be immersed in said liquid, a cylinder and pneumatically operated piston for raising and lowering` said electrodes in said liquid, valves for controlling motive fluid for said piston, a cam for actuating said valves. a hand operated lever adapted to operate said cam and having positions corresponding to definite depths of immersion of said electrodes in said liquid, and means controlled by said piston to restore' said cam to inoperative position upon immersion of said electrodes to a depth corresponding with the position of said hand operated lever.

4. A pneumatically controlled rheostat comprising a tank containing Yliquid and electrodes adapted to be immersed in said liquid, a cylinder and fluid actuated piston to raise and lower said electrodes in said liquid, valves for controlling the supply of motivefluid toV said piston, a hand operated lever having a central Vneutral position and Vadapted to swing both ways to control said fluid to said piston, a hand operated lever having a central neutral position and adapted to swing both ways to control said piston, a cam controlling said valves operable by said actuated lever and restored to normal inoperative position by said piston, a pair of electrical switch controlling valves, and a cam opera le by said hand operated lever to selectively operate said switch controlling valves.

6. A pneumatically controlled rheostat comprising a tank containing liquid and electrodes adapted to be immersed in said liquid, a cylinder and fluid actuated piston to raise and lower said electrodes in said liquid, valves for controlling the supply of motive fluid to vsaid piston, a hand operated lever having `a central neutral position and adapted to swing both ways to control said piston, a cam controlling said valves operable by said hand actuated lever and restored to normal inoperative position by said piston, electrical switch controlling valves selectively operable by said hand operated lever, and safety stop means to limit the movement of said hand operated lever, until said electrodes have been removed from said liquid.

7. A pneumatically controlled rheostat comprising a tank containing liquid and electrodes adapted to be immersed in said liquid, a cylinder and fluidactuated piston to raise and lower said electrodes in said liquid, valves for controlling the supply of motive fluid to said piston, a hand operated lever having a central position and adapted to swing both ways to control said piston, a cam controlling said valves operable by said hand actuated lever and adapted to be restored to normal inoperative position by said piston, switch controlling valves selectively operable by said hand operated lever, safety stop means including a pair of plungers controlled by said switch controlling valves to limit the movement of said hand operated lever until the removal of said electrodes from said liquid. Y

8. A pneumatically controlled rheostat comprising a tank containing liquid and electrodes adaptedto be immersed in said liquid, a cylinder and fluid actuated piston to raise and lower said electrodes in said liquid, valves for controlling the supply of motive 'fluid' to said piston, a hand operated lever having a central position and adapted to swing both ways to control said piston, a cam controlling said valves, operable by said hand operated lever and adapted to be restored to normal inoperative position by said piston, electrical switch controlling valves selectively operable by said hand operated lever, safety stop means to limit the move ment of said hand operated lever until said electrodes have been removed from said liquid, and means to restore saidvsafety stop means.

9. A pneumatically controlled rheostat comprising a tank containing liquid and electrodes adapted to be immersed in said liquid, a cylinder and fluid actuated piston to raise and lower said electrodes in said liquid,

valves for controllingthe supply of motive Y fiuid to said piston, a hand operated lever having a central position and adaptedk to swing both ways to control said piston, a cam controlling said valves, operable by said hand operated lever and adapted to be restored to normal inoperative position by said piston, electrical switch controlling valves selectively operable by said hand operated lever, safety stop means to limit the movement of said hand operated lever until said electrodes have been removed from said liquid and means controlled by said piston to restore said safety stop means.

In testimony whereof I have signed thisv specification.

HARRY v. HAIGHT. 

